Polyamines have been implicated in many aspects of cell division. Impairment of the biosynthesis of polyamines by means of enzyme inhibitors is believed to cause a decrease in cell proliferation in mammals. Although the physiological role of polyamines has not been clearly delineated, there is evidence to suggest their involvement with cell division and growth, H. G. Williams--Ashman et al., The Italian J. Biochem. 25, 5-32 (1976), A. Raina and J. Janne, Med. Biol. 53, 121-147 (1975) and D. H. Russell, Life Sciences 13, 1635-1647 (1973).
Polyamines are also known to be essential growth factors for certain microorganisms, as for example E. coli, Enterobacter, Klebsiella, Staphylococcus aureus, C. cadaveris, Salmonella typhosa and Haemophilus parainfluenza. There is evidence to suggest that polyamines are associated with both normal and neoplastic mammalian cell growth, there being an increase in both the synthesis and accumulation of polyamines following a stimulus causing cellular proliferation. It is also known that there is a correlation between polyamine formation and the activity of the decarboxylase enzymes of ornithine, S-adenosylmethionine, arginine and lysine. The term polyamine is taken to include the diamine putrescine and the polyamines spermidine and spermine. Putrescine is the decarboxylation product of ornithine, catalyzed by ornithine decarboxylase. Putrescine formation may also occur by decarboxylation of arginine to form agmatine which is hydrolyzed to give putrescine and urea. Arginine is also involved in ornithine formation by action of the enzyme arginase. Activation of methionine by S-adenosylmethionine synthetase forms S-adenosylmethionine which is decarboxylated, after which the propylamine moiety of activated methionine may be transferred to putrescine to form spermidine or the propylamine moiety may be transferred to spermidine to form spermine. Hence, putrescine serves as a precursor to spermidine and spermine and additionally has been shown to have a marked regulatory effect upon the polyamine biosynthetic pathway in that it has been shown that increased synthesis of putrescine is the first indication that a tissue will undergo renewed growth processes. Cadaverine which is the decarboxylation product of lysine has been shown to stimulate the activity of S-adenosylmethionine decarboxylase and is known to be essential to growth processes of many microorganisms, for example, H. parainfluenza.
Very little is known of the role of polyamines in algal growth. The occurrence of polyamines in algae has been reported, but little is known about their biosynthetic pathways in algae. Brachet et al., C.R. Acad. Sc. Paris, Serie D, 287, 1289-92 (1978), has shown that DL-.alpha.-methylornithine arrests development of sea Urchine eggs, and prevents the regeneration of the algae, Acetabularia mediterranea, via the inhibition of nuclear RNA synthesis.